How Can I Accurately Measure JavaScript Function Execution Time?

Measuring Execution Time of a Function with JavaScript

Determining the execution time of a function is a crucial task in performance optimization. In JavaScript, several approaches can be used to measure this time accurately.

Using performance.now()

The performance.now() API provides a high-resolution timestamp measured in milliseconds. The following syntax demonstrates how to use it:

const startTime = performance.now();

doSomething(); // Function to be measured

const endTime = performance.now();

console.log(`Function call took ${endTime - startTime} milliseconds`);

Using console.time()

The console.time() and console.timeEnd() functions provide a convenient way to measure execution time. The syntax is as follows:

console.time('doSomething');

doSomething(); // Function to be measured

console.timeEnd('doSomething');

Note that the string passed to console.time() must match the string passed to console.timeEnd() for proper time recording.

Additional Notes:

• In Node.js, the performance class needs to be imported using const { performance } = require('perf_hooks');.
• The performance.now() method is available in all major browsers, including IE9 and above.
• The console.time() and console.timeEnd() functions are part of the Living Standard (ES2019) and may not be supported in older browsers.

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